U.S. Pat. No. 6,599,225, incorporated herein in its entirely by reference, discloses a relatively recently designed carton for the packaging of liquids and/or other pourable materials. This carton is of the gable-top variety and includes a pour spout affixed to one of the two major inclined panels which define the closed top end of the carton. The advent of this use of pour spouts on one of the major top panels of the carton introduced a production dilemma, namely, the presence of the pour spout rendered the new carton “handed”. That is, the carton assumed either “left handedness” or “right handedness” with respect to the movement of the carton through a “form, fill and seal” packaging machine. Whereas it was possible with non-handed gable-top cartons to increase the overall output of a given packaging machine by merely adding to the existing machine a second line of production. The advent of the pour spout, such mere duplication of the first production line with a second production line was made impossible by reason of the need for a pour spout (at times referred to as a “fitment”) attachment and heat sealing apparatus to be added to the machine laterally of the production line, ie. projecting perpendicular to the direction of movement of cartons through the machine. The required positioning of this fitment attachment apparatus dictated that the hole in the top panel of the carton into which the fitment was to be inserted and sealed had to face laterally outwardly of the direction of movement of the production line. To add a second production line required a second fitment attachment apparatus, but because the hole into which the fitment was to be inserted and sealed had to face outwardly of the second production line, the cartons moving along the second line were rotated 180 degrees (ie., flipped over front to back) relative to the orientation of the cartons moving along the first line. This situation prevented the common use by both the first and second lines of certain common components of the production machine, thereby negating the prior ability to gain productivity by doubling the production lines. In particular, it became impossible to close the bottom of the carton using a single pressure pad as had been possible prior to the advent of the addition of a pour spout on the top end of the carton.
As is well known in the art, the sealing of the bottom end of a paperboard laminate-based carton requires that the erected carton be fitted over a mandrel having a distal end carrying a pressure pad. Thereafter, the several folds required to shape various flaps, tabs and panels into a flat bottom closure for the carton must be brought into their respective overlying relationships. While held in such relationships, the flaps, tabs and panels are heated to effect a sealing of these several folded flaps, tabs and panels to one another in a manner which precludes leakage (particularly of liquids, gases and/or flavours) into or out of the finished carton. In some such combinations of infolding and overlaying of the bottom-forming flaps and panels of the carton, there exists multiple layering of the paperboard laminate, severe bending of the laminate at the folds, and particularly at corners of folds, etc. In the prior art, the problem of sealing of the bottom-forming flaps and panels of the carton has been approached through the addition of more sealing polymeric material to the facing surfaces of the folded laminate, skiving the outboard edges of certain of the flaps or panels to minimize the overall thickness of the folds at various locations over the bottom of the carton, altering the folding pattern of the flaps and/or panels, and other measures intended to enhance the sealability of the bottom-forming components.
One approach to the multiple production line concept has been to provide a “non-handed” sealing fin for the bottom of the carton, thereby allowing the use of a single pressure pad for both the first and second production lines. This general concept has proven effective for use with cartons intended to be used for packaging of milk, juices, and similar food-type liquids. However, problems have been found when this prior concept has been employed for forming the bottoms of cartons which are intended to be filled with certain other products, such as cooking oil, for example.
U.S. Pat. No. 6,599,225 depicts one embodiment of a blank for a carton having a square or rectangular footprint, the bottom end of which includes panels and flaps which, when infolded toward the central axis of the erected carton, form a closure for the bottom end of the carton and which includes a “non-handed” sealing fin. With respect to the bottom closure of the depicted carton blank, it is noted that the blank depicted in this patent is divided by vertical fold lines into first, second, third, fourth and fifth vertical side panels. When erected, this flank forms a tube of rectangular or square cross-section, the first, second, third and fourth panels defining the four sides of an erected carton. A relatively narrow fifth side panel is employed as a side sealing panel to close the tubular shape of the erected carton.
Closing of the bottom end of the tubular carton, prior to filling the carton, is accomplished by the cooperative infolding of major end panels, flaps and tabs which are integrally formed with respective ones of the bottom ends of respective ones of the first-fourth side panels and the fifth panel which serves as a glue panel for retaining the first-forth side panels in their tubular-forming relationship. Each of the first-fourth major bottom panels includes an integrally formed minor bottom panel appended to the outboard side edge thereof. Concomitantly with the infolding of the major bottom panels, the bottom closing operation further folds the second and third minor bottom panels along angular score lines and of the second major bottom panel and angular score lines of the fourth major bottom panel to define triangular gussets on each of the second fourth sides of the erected carton. The apices of these gussets meet and/or partially overlap at the center of the bottom of the carton creating a multilayered grouping of the bottom panels adjacent the center of the carton bottom. Sealing of this multi-layered grouping of the gussets' apices, it will be recognized that folding of the carton material (commonly laminated paperboard), imparts severe stress to the carton material along the fold lines and particularly at the apex of each gusset, with attendant tendency for the carton material to delaminate, crack or otherwise lose its integrity.
Completion of the sealing of the bottom of the carton is effected by means of seal fin panels which are integrally formed along the outboard edges of the first and second major bottom panels. As the gussets are formed in the course of infolding of the major and minor bottom panels, these seal fin panels move into overlying registration with one another and eventually their overlying faces are heat sealed to one another. Thereupon the fin seal so formed is folded back into overlying relationship with one of the major bottom panels. Being “non-handed”, the seal fin acceptably may be folded back upon a selected one of either that major panel which is located on the same carton side as the location of the pour spout or folded back over the other of the two major panels. (See FIG. 12 of U.S. Pat. No. 6,599,225 which depicts left-handedness or right-handedness of the erected carton).
Efforts to minimize the deleterious effects of the infolding of the major and minor panels which define closure of the bottom of an erected carton have included cutting away a portion of the blank between the opposite ends of the first fin panel at the ends of their adjacent second minor panels and between the end of the second fin panel and the end of its adjacent third minor bottom panel. Also, terminating the second fin panel short of the fifth glue panel has been practiced. All of these measures attempted to minimize folding stresses and overlapping of layers of the carton material. Moreover, the outer edges of the fin panels have been tapered in a direction away from their respective center fold lines to enhance parallelity of folding of these minor panels.
Irrespective of these and other measures of like nature, effective sealing of gable-top type cartons having pour spouts has been less than satisfactory. This is especially so with the advent of the use of this type carton for such pourable products as cooking oil, etc., where the product is more demanding on the integrity of the bottom sealing of the carton.